To mount an electronic component, such as a semiconductor, on a printed circuit board of electronic equipment or to assemble an electronic component, such as a semiconductor, solder or an adhesive agent is used. Particularly, soldering cannot be performed on an electronic component made of ceramic or the like without performing any treatment. In view of the above, pads formed of a plating film are formed on a surface of an electronic component workpiece, and solder bumps (bulges) are formed on the pads. Thereafter, soldering is performed using the bumps.
Conventionally, a method which uses a solder paste is used as a method for forming solder bumps in many cases. A solder paste is applied on a plating film of a workpiece by a printer or a dispenser and, thereafter, the solder paste is subjected to reflow heating so as to melt the solder paste to form bumps. This method enables low cost. However, on printing, there is a lower limit on the separation at which printing can be performed and hence, bumps which correspond to a fine circuit pattern cannot be formed.
There is also a method for forming a bump by making use of a solder ball. Fine solder balls are mounted on an electronic component workpiece, and the solder balls are subjected to reflow heating thus forming bumps. With the use of such a method, bumps which correspond to a fine circuit pattern can be formed. However, cost for solder balls per se is high so that cost increases as a whole.
As a method for forming bumps which can manage a fine circuit pattern at low cost, a so-called molten solder method has been attracting attention where molten solder is discharged so as to form solder bumps. For example, a solder deposition device disclosed in PTL 1 described below is known as a device for realizing the molten solder method. In this solder deposition device, a nozzle opening portion of a vessel which stores molten solder is caused to scan in the horizontal direction thus efficiently supplying molten solder to a plurality of portions. A bump forming device is also known which includes a mechanism for lifting a nozzle head from a mask after the operation is finished and the nozzle head is cooled (for example, PTL 2 described below).